60-81-identifiers

[pvdbosch]

Pull request for #60 and #81 .

New section "Identifier" under document archetype.

I moved some paragraphs from the "API specifications" chapter to avoid duplication, and put a reference in its place.

[pvdbosch]

REST WG reviewed PR.

One comment from Bert in WG, on designing new identifiers:

• identifiers may get widespread usage outside of the initial API where it was defined, e.g. in client's system, document administration, ...
• think about governance and lifecycle of the identifiers
• Designing identifiers in a URI structure (cfr ICEG URI standard) is useful because it makes the identifier context-independent and more self-descriptive. A REST API may choose to use a shorter API-local form of a URI identifier because of practical considerations.

I'll add this to the PR and submit to review to Bert.

[pvdbosch]

Updated the PR based on Bert's feedback; in the "choice of identifier" section

[pvdbosch]

reviewed and approved by WG